Production of hollow sections on an extrusion press



H. PRODUCTION OF HOLLOW SECTIONS ON AN April 29, 1969 H. GRoos ET AL EXTRUSION PRESS Sheet Filed April 12, 1966 Apnl 29, 1969 H. H. GROOS ET AL 3,440,854

PRODUCTION OF HOLLOW SECTIONS ON AN EXTRUSION PRESS Sheet 2 of 2 Filed April 12, 1966 United States Patent US. Cl. 72265 19 Claims ABSTRACT OF THE DISCLOSURE A method of extrusion, and an extrusion press, in which the exit end of the container is temporarily closed by a plug applied to the exit side of the die, the billet is then pierced in the container, with the container and the die in their normal extrusion positions but with the die aperture thus closed. The plug is then removed laterally from the path of the extruded product, and extrusion is thereupon started.

This invention relates to a method for the production of hollow sections, particularly tubes and tube ingots on an extrusion press, and also to means for carrying out the method.

For the production of hollow sections on extrusion presses, pierced billets are required. The piercing is effected either in a separate piercing appliance or in the press itself. Effecting the piercing of the billet in the extrusion press has the special advantage that no supplementary piercing press is required. In one known extrusion press, the container is mounted upon the die during the piercing operation, so that the core is expelled through the die aperture. Since, under these circumstances, before the termination of the piercing operation, billet material is already issuing through the aperture of the die, the loss of material owing to the formation of the piercing core is particularly great. It has therefore been suggested that during the piercing operation, the container aperture facing the die should be closed, with a transversely slidable closure plate being provided between the die and the container. As in the case of a piercing press, the piercing core that is used is thereby restricted to a very small amount. The cycle of operations of such a press, however, lasts a comparatively long time. After the billet has been pierced, the container, for the transverse displacement of the closure plate, has to be lifted, and then advanced, together with the pierced billet, into the extrusion position, that is, right up to the die. This has a disadvantageous effect not only upon the output or efficiency of such a press, but above all upon the durability of the edges of the tools that participate in the piercing and extruding operations.

Although, during the piercing operation, the die is protected by the closure plate from the action of heat, the contact time of the mandrel and of the container bushing with the hot billet material is comparatively long. Since the wear of these members is adversely influenced by the contact time with the hot billet, the working life of these members is corresopndingly short. The mandrel absorbs the greater part of the tool costs since, its weight is much greater than that of the die. Since the cost of the tools represents an important factor in the economy of an extrusion press, one is constrained to keep this cost as low as possible. This can only be attained if the contact time of the tools participating in the piercing and extrusion, and particularly that of the piercing mandrel, is restricted ice to a minimum. It would be obvious to reduce the contact time by keeping the displacement path of the container after the completion of the piercing operation as short as possible. This could be attained by making the die-holder transversely displaceable, and in which case it serves, in its second position, as a cover plate for the container aperture. In this case, after the termination of the piercing operation, the container and the piercing-mandrel cylinder would only need to be relieved of load for the purpose of the transverse displacement of the die-holder, and thereupon, for the centering of the container upon the die, it would only need to be displaced a few millimeters in the direction of the die. Then, after pushing the piercing core through with the aid of the mandrel, the extrusion operation could be started immediately.

The present invention has approached the problem of shortening the contact time still further, and beyond the normal development. According to the invention, this is effected by the fact that the piercing of the billet is achieved in the extrusion-press position of the container and the die, and during the piercing operation the exit side of the die aperture is closed. Owing to the fact that the die already serves as a closure means for a partial region of the billet-container, and additional movement of the billet-container need no longer be effected after the end of the piercing operation so that immediately after the opening of the closure means for the die aperture, the expulsion operation for the piercing core and the extrusion operation can start. For the closure of the die, a closure plate displaceable transversely to the extrusion axis may advantageously be arranged behind the die which may advantageously co-operate with the die-supporting ring arranged in a known manner between the die and the pressure plate, with both being arranged horizontally on the same plane, and the die-supporting ring upon the closure plate being pushed in below the die aperture, and being positively displaced transversely. In order, after the termination of the piercing operation, to slide the die-supporting ring into its position beneath the die, it is an advantage if it is subjected to the force of stressed cup springs, and is brought, on the basis of the pushing-in, beneath the closure plate in the out-of-action position. For the guidance of the die-supporting ring and of the closure plate, there preferably serves a slot in the die-holder, with this slot being arranged underneath the die and extending transversely to the axis of extrusion.

In a further development of the invention the die aperture is closed and opened with a closure plug slidable and supportable in the axis of the press instead of with a transversely displaceable closure plate. The use of a closure plug displaceable in the extrusion direction for the die aperture has the advantage that after the end of the piercing operation, a commencement can be made immediately, without interruption, with the expulsion of the piercing core and thereupon with the extrusion of the hollow body. An interruption of the working rhythm, from the placing of the billet in the container until the extru sion thereof as a finished hollow section, thus need no longer be effected so that the time during which the tools participating in the piercing and extruding operations are exposed to the heating action coming from the billet reaches its minimum value.

In order that the switching delays occurring during the individual working cycles may largely compensate for one another, it is advantageous to proceed in such a way that the initiating of the return stroke for the closure plug is effected when the mandrel of the extrusion press, shortly before the end of the piercing operation, is switched on to slow travel, with the speed of the return stroke of the closure plug being substantially greater than the speed of the piercing mandrel. With a press outlet extending in an arcuate form, the supporting of the closure plug is advantageously elfected by a hydraulic cylinder arranged in the axis of the press behind the press outlet. In this case, the part of the run-out channel located in the range of displacement of the closure plug is so arranged that it can be brought out of the axis of the press. In order to keep the displacement travel of the closure plug small, it is rockably arranged in the axis of the press. Advantageously, however, the closure plug is so arranged in the axis of the press as to be rockable jointly with the hydraulic cylinder. In this way the closure plug, in any position, remains in an operative connection with the hydraulic cylinder. A simple synchronizing of the deflection of the run-out channel out of the press axis with the inward swing of the closure plug into the press axis, and conversely, is thereby obtained, if the part in question of the run-out channel forms a rocking unit with the closure plug. Advantageously the bolster of the press is provided, underneath the pressure piece, with two recesses for the press axis opposite to one another for the accommodation of the run-out channel and the closure plug when out of operation. The displacement travel of the closure plug is thereby kept particularly short.

Since the rockable run-out channel member, during the piercing operation, is rocked away from the stationary run-out channel members, this may be closed in as short a time as possible after the retraction of the closure plug into its initial position, with the stationary run-out channel members again, in order that the operation, following thereupon of expelling the piercing core, and the extrusion of the hollow section, may be able to be carried out without interruption and without disturbance.

In a further development of the invention, the procedure is therefore such that the rockable run-out channel member is locked to the stationary run-out channel members before the returning closure plug is braked. The inward swing of the run-out channel member into the extrusion axis is therefore already carried out at the moment when the closure plug has travelled back so far that it can be rocked sideways. The extrusion operation can thereby already be commenced before the closure plug has come to rest through being braked. The hydraulic cylinder, for supporting the closure plug, receives for this purpose an extra stroke which corresponds to the length of the brake travel of the closure plug after it has rocked out of its closure position. During the return stroke of the closure plug, the rockable member of the run-out channel may advantageously be positively locked with the stationary members of the run-out channel. Owing to the positive control of the closure plug during its return stroke for closing the rockable run-out channel member with the associated stationary run-out channel members, additional control elements for rocking the run-out channel member inwardly into its working position are not required.

In a known manner, the extruding of the billet is effected with the aid of a lubricant. For this purpose, a lubricant-forming disc of glass-graphite mixtures or other mixtures is placed between the die and the billet. In vertical extrusion presses in order that the lubricant constructed as a disc, may not be destroyed as the billet is being introduced into the container, it has hitherto been necessary to take additional precautions in order that it may become effective to take into consideration losses of time up to the commencement of the working cycle of the press. With the aid of the closure plug according to the invention, such precautions may be dispensed with, if, for the introduction of the closure plug into the die aperture, two switching positions are allocated to the closure plug so that in the first switching position, it projects beyond the die aperture by a definite amount corresponding to the thickness of the disc of lubricant, and is moved back after the introduction of the billet into the container, into the second switching position, in which it registers with the die aperture on the container side. The

shock of the billet being introduced into the container is thereby taken up by the closure plug, and destruction or failure of the lubricant disc is prevented. For the attainment of the switching position of the closure plug for the interception of the billet, the hydraulic cylinder for the supporting of the closure plug is constructed with an excess length corresponding to this switching position.

The hydraulic cylinder that provides the supporting force is preferably made controllable in order that the speed of lift or stroke for the closure plug may be accurately adaptable to the procedures required during a working cycle of the press. This is also particularly important with respect to its brake travel.

constructional examples of the invention are illustrated in the accompanying drawings, in which:

FIGURE 1 is a side view of a vertical extrusion press partly in cross section and partly in elevation;

FIGURE 2 is a view in section in the region of the container and of the thrust plate, and a closure plate, displaceable transversely to the axis of extrusion, being provided as a closure for the die aperture;

FIGURE 3 is a view taken along the line III-III in FIGURE 2, the view looking in the direction of the arrows;

FIGURE 4 is a view partly in section and partly in elevation of the region of the container and bolster, and also of the press outlet with a rockable closure plug for sealing the die aperture; and

FIGURE 5 is a view partly in section and partly in elevation of the same region as FIGURE 4, but with a rockable hydraulic cylinder for supporting the closure plug.

In the extrusion press, shown half in section in FIG URE l, 1 denotes the cylinder cross-beam, and 2 the bolster, and these two members are united by means of columns 3, to form a rigid unit. In the cylinder crossbeam 1 is secured a press cylinder 4. A main press plunger 5 and a crossbar 6 form a common displacement unit, with the cross-bar 6 being guided upon the columns 3. A press ram 7 is secured in the crossbar 6. A piercing cylinder 8 is arranged in a cavity in the main press plunger 5, and is therefore displaceable jointly with the latter. A piercing piston 9 and a piercing crossbar 10 likewise form a jointly displaceable unit. A piercing mandrel 11 guided in the bore of the press ram 7 is secured to the piercing crossbar 10. 12 denotes the press-retractors, and 13 the mandrel-retractors. A billet-container 14 is arranged in a billet-container holder 15, and is displaceable in an axial direction for changing die 17. The die 17 is surrounded by a die band 18' resting upon a die-holder .18 in the form of two segments of a cylinder, which bears upon a thrust plate 19, and the latter in turn bears upon a thrust piece 20.

According to FIGURES 2 and 3, the die-holder 18 is exchangeably arranged in a recess 23 in a rotary tool arm 22. The rotary tool arm 22 is rockable through about a shaft 24. Underneath the die 17, and between the two segments of the die-holder 18, is provided a slot 25 extending transversely to the extrusion axis, and serving to guide a closure plate 26 for closing a die aperture 30. By pushing in the closure plate 26-, a die-supporting ring 27 is displaced into the position illustrated, in which, by means of a thrust rod 28, cup springs 29 are stressed. Upon the closure plate 26 being slid back, the supporting ring is pushed back by the springs 29 into its prescribed position underneath the die aperture 30. By an abutment ledge 31 which is located in a guiding bore for the thrust rod 28, and against which annular surface 31a of the thrust rod 28 bears, the exact position of the die-supporting ring 27 underneath the die aperture 30 is fixed. The closure plate 26 can be displaced into its operative position beneath the die aperture by known power means, such as by hydraulic means. In order that the rotary tool arm 22 may be able to turn, the closure plate 26 is withdrawn after the piercing operation, into the position 26' (dot-dash lines) in FIGURE 3.

According to FIGURE 4, a closure plug 33, rockably supported about an axis 32 serves for the closure of the die aperture. In a closure-plug guide 34 the closure plug 33 is supported in an axially displaceable manner. The closure-plug guide 34 has on sides opposite to one another guiding bushes 36 (FIGURE 1) which are guided in bearing bolts 35. The bearing bolts 35 are secured to anchors or tie-rods 37 which at the same time carry a crossbar 38 for accommodating a lifting cylinder 39 for actuating the closure plug 33. To the rockably supported closure-plug guide 34 is at the same time secured a rockable run-out channel member 40 so that this member forms a swinging unit together with the closure plug 33. Underneath the thrust-piece the bolster 2 is provided, upon opposite sides of axis 41 of the press, with recesses 42 and 43 for the accommodation of the upper portion of the closure plug 33 and the rockable run-out channel member 40. In FIGURE 4, the closure position of the runout channel member 40 is represented together with stationary guiding-channel members 44 and 45. In this position, the closure plug is located in the recess or cavity 42 in the bolster. In the closure position of the closure plug, according to 33' in FIGURE 4, the rockable run-out channel member is located in the recess 43, as shown at 40'. The rocking movement of the closure plug 33 and the run-out channel member 40 is etfected by a diagrammatically represented lifting cylinder 46, piston rod 47 of which is for this purpose pivotally linked to a lug 48 arranged on the run-out channel member 40. Upon the closure plug 33 rocking into the working position, its foot 49 engages in a corresponding recess 50 in a lifting piston 51. In order that the rockable press run-out member 40 may register with the stationary guiding-channel members 44 and 45 in its operative position, an abutment 52 is secured thereto. To the closure-plug guide 34 is secured an abutment pin 55 which co-operates with a groove 56 in the closure plug 33. The end of the groove 56 defines an abutment surface of the closure plug 33 which serves for the accurate fixing of the foot 49 of the closure plug 33 in relation to the recess 50 in the lifting piston 51.

According to FIGURE 5, the closure plug 33 is connected fast with the lifting piston 51. For rocking the lifting piston 51 out of its operative position, the lifting cylinder 39 is in this case inserted in a rockable crossbar 54, which is rockable about an axis 53 together with the lifting cylinder 39. This arrangement has the advantage over the arrangement according to FIGURE 4 with ex clusive rockability of the closure plug 33, so that the axis of oscillation 53 can be located farther down than the axis 32 of FIGURE 4, and that the amplitude of oscillation of the closure plug 33 and the press run-out member 40 can be kept smaller. Owing to this, the recesses 42 and 43 in the bolster 2 need be given only small dimensions. A further advantage is that the rocking of the closure plug out of and into the press axis can be effected more quickly than with the construction shown in FIGURE 4. A guide 55 guides the closure plug, and at the same time serves for securing the rockable press run-out member 40. The guide 55 is connected by a laterally flared tube 55a with the rockable crossbar 54. To the lug 48 is attached the displacing piston rod 47 for rocking the closure plug 33 including the associated press run-out member 40. Diagrammatically represented abutments 57 and 58 are adjustable, and serve for limiting the amplitude of swing, and at the same time for fixing the closure plug and the run-out channel member 40 relatively to the extrusion axis 41.

In the various figures of the drawings, the same references are employed for similar elements.

In the piercing and extruding of the inserted billet, the procedure is as follows: before introducing the billet into the container 14, the closure plug 33 is first rocked into the axis 41 of the extrusion press by suppling pressure fluid to the piston of the hydraulic cylinder 46. Thereupon, the lifting piston 51 is supplied with pressure medium, and the closure plug 33 is advanced into the position 33 (FIGURE 5, shown dotted), so that it projects by a small amount through the die aperture into the container 14. Thereupon, first lubricant ring 59 and then billet 60, which has meanwhile been heated, are put into the container 14. Since the closure plug projects beyond the lubricant ring 59, the billet 60, upon its admission into the container 14, is engaged by the closure plug 33 so that it cannot harm the lubricant ring 95. Thereupon, the closure plug 33 is retracted into the position 33 according to FIGURE 4. In this position it lies in one plane with the surface of the die 17 that faces the container aperture, and with the surface of the dieholder 18. Thereupon, by supplying motive fluid to the main press plunger 5, the press ram 7 together with the piercing mandrel 11, is advanced in the direction of the billet-container 14 until the press ram 7 and the piercing mandrel 11 come into contact with the inserted billet 60. By thereupon supplying pressure fluid to the piercing piston 9, the piercing of the billet 60 is effected, with the die aperture being closed by means of the closure plug 33. Shortly before the termination of the piercing operation, the supply of pressure fluid to the piercing cylinder 8 is throttled so that the piercing mandrel 11 advances more slowly right to its end position. During this reversing operation, by appropriate energizing of the lifting piston 51, the closure plug 33 already loads the latter in the rocking direction. As soon as the closure plug 33 has left the stationary guiding-channel member 45 which is secured in the thrust piece 20, it is immediately swung out sideways, and at the same time the guiding-channel member 40 is swung into the axis of the extrusion press. The deflection of the closure plug 33 out of its operative position initiates its braking operation, which is ended in the position 33 (FIGURE 5, shown dotted). The lifting cylinder 39 is lengthened by an amount it corresponding to the braking distance. The braking of the lifting cylinder is effected by a throttling body 61 which co-operates with the supply pipe 62 during the withdrawal of the lifting piston 51. Since in this way the return stroke of the closure plug 33 can be carried out at an increased speed, and therefore the time required for the slewing of the closure plug 33 and of the run-out channel member 40 is very short, the shearing operation for the piercing core can follow directly upon the piercing operation. After the piercing core has been sheared off, the pierced billet is extruded by supplying further motive fluid to the main press plunger 5, by extrusion corresponding to the free cross section between the piercing mandrel and the die aperture. After severing the extrusion residue from the extruded product, and removing the extrusion residue from the container, the cycle of operations can be started anew.

Owing to the fact that the billet 60*, during the piercing and extruding operation, is only in contact with the tools participating in these operations for a short time, their life, as compared with the traditional methods and the appliances employed therewith, is considerably lengthened, and an economical extrusion, particularly of steel, is thus obtained.

We claim:

1. A method for the production of hollow sections, particularly for tubes and tube ingots, on an extrusion press, comprising the steps of closing the container on the die side, the closure being on the outer side of the die, effecting the piercing of the billet in the container of the extrusion press with the container and the die in their normal extrusion positions, and with the die aperture closed, and then removing the closure from the die aperture in a direction other than the exit direction of the extruded product.

2. An extrusion press for the production of hollow sections, comprising movable closure means that can be applied to the outer side of the die so as to close the billet-container and the die, a piercing mandrel capable of piercing a billet located in the container of the extrusion press while the container and the die are in their normal extrusion positions and the die aperture is closed by the said closure means and actuating members for removing the closure means laterally out of the path of the extruded product.

3. An extrusion press as claimed in claim 2, the movable closure means being a closure plate which is slidable transversely to the axis of extrusion.

4. An extrusion press as claimed in claim 3, further comprising: a bolster, a thrust plate supported by the bolster, and a die-supporting ring arranged in the same plane as the closure plate between the die and the thrust plate, so that when the closure plate is slid into alignment with the die aperture the die-supporting ring is positively displaced transversely to the axis of the die.

5. An extrusion press as claimed in claim 4, further comprising cup springs adapted to be stressed when the closure plate is slid into alignment with the die aperture, and to urge the die-supporting ring back into axial alignment with the die when the closure plate is withdrawn.

6. An extrusion press as claimed in claim 4, the dieholder being formed with a slot, extending transversely to the axis of extrusion, in which the closure plate and the die-supporting ring can slide.

7. An extrusion press as claimed in claim 2, the movable closure means being a closure plug supported in the axis of the press, and adapted to co-operate with the die aperture and to be displased relatively thereto in the said axis.

8. An extrusion press as claimed in claim 7, further comprising an arcuate press outlet, and a hydraulic cylinder arranged in the axis of the press, behind the press outlet, for supporting the closure plug.

9. An extrusion press as claimed in claim 8, the closure plug being rockably arranged in the axis of the press.

10. An extrusion press as claimed in claim 9, the hydraulic cylinder being rockable, together with the closure plug, in the axis of the press, and the press further comprising a run-out channel located within the range of displacement of the closure plug, a part of this run-out channel being movable out of the axis of the press.

11. An extrusion press as claimed in claim 10, the part of the run-out channel located within the range of displacement of the closure plug constituting, together with the closure plug, an oscillating unit.

12. An extrusion press as claimed in claim 11, further comprising a thrust-piece, a bolster beneath the thrustpiece, the bolster being formed with two recesses, on opposite sides of the axis of the press, for the accommodation of the run-out channel and of the closure plug in the inoperative position thereof.

13. An extrusion press as claimed in claim 12, further comprising means for braking and returning movement of the closure plug, the movable part of the run-out channel member being adapted to come into alignment with the remainder of the run-out channel member before the returning movement of the closure plug is braked.

14. An extrusion press as claimed in claim 13, the hydraulic cylinder having such an additional length as corresponds to the braking travel of the closure plug after its deflection out of its closure position.

15. An extrusion press as claimed in claim 14, the movable part of the run-out channel member being adapted to register with the stationary part thereof during the return stroke of the closure plug.

16. An extrusion press as claimed in claim 15, further comprising means for impelling the piercing mandrel for its piercing stroke, means for reducing the speed of advance of the piercing mandrel shortly before the end of the piercing operation, the return stroke of the closure plug being initiated when this reduction occurs, and the speed of the return stroke of the closure plug being substantially greater than the speed of the piercing mandrel.

17. An extrusion press as claimed in claim 16, further comprising: means for introducing the closure plug into the die aperture, including means for adjusting the closure plug into two different positions in succession, namely a first position, in which the closure plug projects by a definite amount beyond the die aperture, and a second position (after the billet has been introduced into the container) in which the closure plug is flush with the container side of the die aperture.

18. An extrusion press as claimed in claim 17, the hydraulic cylinder that supports the closure plug being given an excess length corresponding to the first position of the closure plug.

19. An extrusion press as claimed in claim 18, the hydraulic cylinder that provides the supporting force for the closure plug being controllable.

References Cited UNITED STATES PATENTS 682,359 9/1901 Keithley 72266 2,128,705 8/1938 Hatebur 72256 2,388,558 11/1945 Loewy 72265 2,491,897 12/1949 Lorant 724-265 2,738,063 3/1956 Billen 72264 MILTON S. MEHR, Primary Examiner. 

